Commitments and Contingencies (Tables)

3 Months Ended

Mar. 31, 2018

Commitments And Contingencies Disclosure [Abstract]

Schedule of Long-term Commitments

The following is a schedule of future payments under PPAs, minimum lease payments with non-cancelable lease terms in excess of one year, and other net purchase obligations/commitments at March 31, 2018:

					Long-term Service
	Purchased		Operating		Agreements/Capital		Clause Recoverable
(millions)	Power		Leases		Projects		Commitments		Total
Year ended December 31:
2018	$	15	$	2	$	412	$	359	$	788
2019		0		2		155		237		394
2020		0		2		21		186		209
2021		0		2		15		155		172
2022		0		2		8		150		160
Thereafter		0		36		23		1,124		1,183
Total future minimum payments	$	15	$	46	$	634	$	2,211	$	2,906